Wyniki wyszukiwania - BazTech

1

Mid-Holocene horizons of strongly decomposed peat and problems of dating paleohydrological changes in mires in the Racibórz basin, Southern Poland

Wójcicki K. J., Nita M.

Geochronometria

|

2017

|

Vol. 44, no. 1

162--174

EN

During litho-stratigraphic studies of deposits in small mires in the upper basin of the Oder River, mid-Holocene hiatuses identified by the presence of horizons of strongly decomposed peat (HSDP), were identified at four sites. Radiocarbon dating results indicate long (103 years) breaks in peat accumulation and the dates obtained from the underlying layers of deposit are inconsistent with the pollen record. In order to explain these discrepancies, an attempt was made to recreate the conditions of HSDP formation under the influence of endo- and exogenous factors determining peatland productivity. In the light of macrofossil analysis, the development of HSDP during the Atlantic and Subboreal periods, when the humidity of habitats decreased, occurred at an advanced stage of development of swamps with Alnetea glutinosae forest communities. The gradual rise in water levels in the mires that started in the Subboreal period and intensified during the Subatlantic period was recorded as a slow shift in vegetation towards non-forest, sedge-moss communities belonging to the Magnocaricion alliance or the Scheuchzerio-Caricetea nigrae class. One consequence of the mechanism of HSDP formation is the existence of limitations on the dating of the duration of the dry phase owing to the presence of organic matter of different ages in the degraded peat layer. The determination of the age of wet phases offers better prospects. In the light of radiocarbon dating, which is essentially in line with the pollen analysis results, the transition towards positive peatland productivity occurred between ca. 9th century BC and 7th century CE.

2

Geneza równin torfowiskowych w dolinach rzecznych dorzecza górnej Odry

Wójcicki K. J.

Landform Analysis

|

2015

|

Vol. 30

41--48

PL

Artykuł poświęcony jest problematyce genezy równin torfowiskowych w strefie „staroglacjalnej” południowej Polski. W objętych badaniami dolinach Kłodnicy i Osobłogi, torfowiska rozwinęły się głównie w obniżeniach starorzeczy. Akumulacja biogeniczna została zainicjowana w różnych fazach późnego glacjału i holocenu, w szczególności w młodszym dryasie i okresie preborealnym w przypadku form położonych u podnóży zboczy doliny, oraz w fazie subborealnej i subatlantyckiej w przypadku mniej licznych form zlokalizowanych w strefie proksymalnej równiny zalewowej. W dolinie Kłodnicy zostały zidentyfikowane następujące etapy rozwoju form akumulacji biogenicznej: (1) szybki przyrost osadów we wczesnym i prawdopodobnie środkowym holocenie, (2) ograniczenie tempa akumulacji u schyłku mezoholocenu(?) i w starszym neoholocenie, (3) ponowny wzrost tempa akumulacji osadów w młodszej części późnego holocenu. Rozwój większości form akumulacji biogenicznej został zatrzymany w ostatnim tysiącleciu na skutek antropogenicznego ożywienia procesów fluwialnych i denudacyjnych.

EN

The article discusses the origin of peatland plains in the ‘old glacial’ zone of southern Poland. In the studied valleys of the Kłodnica and Osobłoga Rivers, peatlands developed mainly in the depressions of oxbow lakes. Biogenic accumulation started in various periods of the Late Glacial and Holocene, particularly in the Younger Dryas and Preboreal phases in the case of forms at the foot of the valley sides, and in the Subboreal and Subatlantic phases in the case of less numerous forms within proximal floodplain. The following development stages of floodplain fens were identified in the Kłodnica valley: (1) the rapid growth of deposits in the Early and possibly in the Middle Holocene, (2) significant reduction in the accumulation rate at the end of the Middle Holocene (?) and in the earlier part of the Late Holocene, (3) the re-growth of sediment accumulation rate in the later part of the Late Holocene. Development of numerous biogenic landforms has been stopped as a result of human-induced acceleration of fluvial and denudation processes in the last millennium.

3

The valley-fill deposits of the Kłodnica River (Southern Poland) : environmental drivers of facies changes from the Late Vistulian through the Holocene

Wójcicki K. J.

Geochronometria

|

2010

|

Vol. 35

49-66

EN

Lithological analyses and radiocarbon dating were used to elucidate the patterns and controls of Late Quaternary valley floor development of the Kłodnica River, the Upper Odra Basin. The research results were discussed with data obtained from valleys of rivers draining piedmont basins and highlands of southern Poland. In consequence, five stages of morpho-sedimentary evolution of the Kłodnica valley were distinguished. In the Late Vistulian a large-scale deposition of channel alluvium took place in the conditions of high river discharges. This sedimentary style probably still existed in the Early Pre-Boreal as long as open grass communities survived in the Kłodnica catchment. The next phase, in the Late Pre-Boreal and Boreal, is characterized by a significant increase in accumulation rate of biochemical facies.. The considerable restriction of minerogenic deposition was connected with widespread of forest and gradual limitation of the river discharges. The third stage began at the decline of the Boreal and was defined by decrease of accumulation rate or even biogenic accumulation break. Synchronously, periodic increases of fluvial activity were noticed in the form of cutoffs of meander loops and overbank deposition in oxbows. The beginning of the fourth period took place not earlier than in the Early Sub-Boreal. This stage was distinguished by renewed peat growth/increase in biochemical accumulation rate and periodic increase in alluviation, generally taking place in the conditions of low channel-forming flows. The latest phase (from the Middle Sub- Atlantic till now) is characterized by common initiation of slope deposition and a rapid increase in fluvial sedimentation, especially overbank and tributary fan facies. An increase in minerogenic deposition occurred in response to human impact, which became more significant from the Roman Period and occurred on a large scale from the early Middle Ages. Older settlement phases, including intense settlement from the Hallstatt Period, were not clearly recorded in the Kłodnica valley fill.